Multituned horn



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Dec. 25, 1928.

.-1 TTORNEY `40 having a plura Patented Dec'. 25, 192s.

UNITED STATES PATENT OFFICE.

MILLER REESE HUTCHISON, OF LLEWELYN PARK, WEST ORANGE, NEW JERSEY, AS-

SIGNOR, BY MESNE'ASSIGNMENTS, TO ACOUSTIC PRODUCTS COMPANY, OF NEW YORK,N. Y., A CORPORATION OF DELAWARE.

EULTITUNED HORN.

v applwaumi mea my 24, 1927.- serm No. masia.

This invention relates to sound propagating devices of theelectromechanical type, in which sound waves produced by a vibratingdiaphragm are selectively re-enforced by res-` onating chambers andimpressed upon th surrounding medium.

In an acoustic device of the ty e employing an open end horn and a mecanical vibrating diaphragm for imparting sound waves thereto, the hornoperates in a manner similar to an open end organ pipe, being resonantto awave having a length twice that of the horn. Such a device has thepropert of re-enforcing most stron ly notes of its undamental frequencyan of responding less strongly to the various overtones thereof. It,

however, is practically incapable of reproducing notes below itsfundamental frequency o and responds but feebly to notes of frequenciesother than its fundamental and overtones.

l Since the timbre of a note is determined largely by the presence orabsence of the various overtones or harmonics, it is desirable toaccurately reproduce such overtones in order that the propagated sounddoes not lose its ori al timbre, and is not distorted.'

e present invention therefore, provides a horn capable of re-enforcingthe mental note and the various overtones thereof in substantially thesame degree. Consequently, by employing a bank of twelve such horns,each'being tuned to a different note comprisin an octavejln thechromatic scale,

the comp ete range of musical frequencies may be accurately reproducedtogether with the various overtones which are originally present.

This is accom lished by'providin a horn ity of resonating c ambers whichare tuned re actively to the fundamental and various armonics, such asthe second and fourth. The chambers may be inter-communicating, andsound waves comprisin compressions and rarefactions may be setup 1n theenclosedmedium by any suitable means, such as a-vibrating diaphragmforming a part o f an electromagnetlc reproducing umt.. The resonatingchambers will then serve `4to select the various notes to which th aretuned which notes will be re-enforc fundathe accompan ing drawin therebyand impressed upon the surrounding medium as sound waves, Waves of otherfrequencies, however which may be impressed upon said chambers by themechanical diaphragm will not be re-enforced to any appreciable extent,and consequently will not be propagated with suiiicient amplitude tointerfere therewith.

The resonating'chambers may be arranged in any desired relationship tothe vibrating diaphragm which is utilized for producing sound wavestherein. One form which has been found to produce satisfactory resultscomprises an open pipe and a closed pipe, Joined end to end, with anaperture for communicating with the surrounding medium located at thejunction point thereof. A third resonating chamber. comprising an openend pipe may be inserted in said aperture and provided at its freeIend'with a flared bell.

The various pipes thus constructed may have free periods of vibrationwhich aremultiples of one another, -as will be hereinafter explained.

The invention also consists in certain new and original features ofconstruction and combinations of parts hereinafter rset forth andclaimed.

.Althou h the novel features which are believed to ie characteristic ofthis invention will be s eciiically pointed out in the claims a endehereto, the invention itself, as to its o ]ects and advantages, the modeof its operation and the manner of its organization, ma

-. be better understood by referring tothe fo lowing description takenin connection with forming a part thereof, in w ich like re erencecharacters have been used to ,denote like parts in the vari'qus figures.Since such lllustration is, howevenplrimarily for pur oses ofdisclossure, it wi be understood t at the structure and the method ofoperation thereof may be modified in various respects without departingfrom the broad spint and scope of the invention.

One embodiment of theinvention has been shown for purposes ofillustration in the accompanyin drawing, in which Fig. 1 i ustrates anacoustic device constructed in accordance with this invention;

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Fig. 2 illustrates a plurality of such devices tuned to the differentnotes of the chromatic scale; and

Fig. 3 illustrates a. modified form of device which may be employed.

In the following description and in the claims the various parts of theapparatus and details of the invention will be identifled by specificnames for convenience, but they are intended to be as generic in theirapplication as the art will permit.

Referring to the drawings more in detail, and in particular to Fig. 1,an acoustic device is disclosed comprising a plurality of pipes 1, 2 and3 forming resonating chambers, which are arranged in inter-communicatingrelationship. Pipes 1 and 2 may be joined end to end, and pipe 3extended at right angles thereto at the junction point of said firstmentioned pipe. The end of pipe 1 furthest from the junction point ofsaid pipes may be closed to form a closed resonating chamber,

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and the corresponding end of pipe 3 may be provided with a bell 4 tofacilitate the propagation 0f the sound waves from said chambers to thesurrounding medium.

An electromagnetic unit 5 of any Well known construction having avibrating diaphragm 6, may be located across the open end of pipe 2 andutilized for imparting vibrations to the various chambers. Unit 5, thedetails of construction of which form no part of the present invention,ma be of the type having a plurality of pole pieces which are energizedin response to a pulsating electric current, and produce a magneticfield of varying intensity. Diaphragm 6 is attracted toward the polepieces by a force proportional to the strength of the magnetic field,and consequently is displaced from its normal position of rest by adistance proportional to the applied current.

The vibrating diaphragm produces compressions and rarefactions in thecontacting gaseous medium, which travel as waves in the variousresonating chambers. Assuming by way of example, that chamber 1 is tunedto a definite frequency, such as note C which corresponds to a wavehaving 512 vibrations per second, it will respond most strongly to thatnote and re-enforce the same, and impress the reenforced sound wavesthrough chamber 3 and bell 4 on to the surrounding medium.

Pipe 1 having a closed end will operate as a closed organ pipe, andconsequently will be resonant to a wave havin a length four times thatof the pipe. Cham er 2 will, however, operate as an open pipe, and willbe resonant to a wave twice the length thereof. Pipe 2 may, therefore,be made half the length of pipe 1, and will then be resonant to note Czhaving 2048 vibrations per second, which is two octaves above the noteC.

Pipe 3 may be given a length equal to that of pipe 1, but being an openend pipe will respond to a wave double its own length, or to t e note Chaving 1024 vibrations per second, which is one octave above the note C.

In the operation of this device, should the note C be impressed upondiaphragm 6 the fundamental will be re-enforced and amplified byresonating chamber 1. The first harmonic thereof, however, willy bere-enforced by resonatin g chamber 3, and the second harmonic, shouldsuch be present, will be reenforced by chamber 2. The device is,therefore, capable of reproducing both the fundamental and the variousovertones in the same proportion in which they are originally present,and consequently the resultant music is not distorted and the originaltimbre thereof is preserved.

As disclosed in Fig. 2, in diagrammatic form, a plurality of the abovedescribed devices may be employed for the reproduction of an entiremusical scale, each of the devices being tuned to a different note.Since there are twelve different notes in the chromatic scale, twelvesuch devices may be employed, and when tuned respectively to the variousnotes comprising one octave of the scale, will serve for theamplificat-ion of the entire musical range. Each individual devicecomprises three resonating chambers which are respectively tuned tothree successive octaves, and each of the chambers is resonant to thevarious overtones thereof. Consequently, the device will serve for theproduction of notes occurring in any octave of the musical scale.

Since the resonating chambers are practically non-responsive to noteslower than their fundamental, any extraneous influences`r such as thoseproduced by static, or by spark disturbances, are effectively suppressedand pre vented from interfering with the resultant music.

In the modification shown in Fig. 3, resonating chambers 1 and 2 areconstructed similar to corresponding chambers illustrated in Fig. 1.Chamber 3 is, however, omitted and bell 4 applied directly to thejunction point of the iirst mentioned chambers. Such an arrangement mayhave the respective chambers tuned to both the fundamental and thesecond harmonic, and due to the ability of each of said chambers torespond to the various overtones, and particularly the first overtone,may operate in a manner similar to the above described device.

The acoustic properties of a sound propagating device constructed asabove are materially superior to those of a simple horn which isincapable of reproducing notes of various frequencies with the sameefficiency. Obviously, if the overtones are not preserved in theiroriginal proportion to the fundamental note, the quality of the music islost. This device, however, not only produces a pleasing effect due toits ability to preserve the original timbre in musical notes, but alsodue to its ability to suppress extraneous noises which are not of amusical pitch.

While certain novel features of the invention have been shown anddescribed and are pointed out in the annexed claims, it will be.

understood that various omissions, substitutions'and changes in theforms and details of the device illustrated and in its operation may bemade by those skilled in the art without departing from the spirit ofthe invention.

What is claimed is:

l1. A sound reproducing device comprising a plurality of resonatingchambers, one of said chambers being tuned to a definite fundamentalfrequency, and the others of said chambers being tuned to overtonesthereof, and means for imparting sound Waves to each of said chambers.

2. An acoustic device comprising a plurality of resonating chamberstuned to different frequencies whereby a plurality of notes maybere-enforced therebyyone of said chambers being tuned to a definitenote, and the others of said chambers being tuned to harmonics thereof.i

3. An acoustic device comprising a vi. brating diaphragm and a pluralityof resonating chambers operatively associated therewith, said chambersbeing tuned respectively to a given frequency and different overtonesthereof.

4:. A device for propagating the various notes of a chromatic scale,comprising a plurality of groups of resonating chambers, each chamber ineach of said groups being tuned to a different fundamental frequencycorresponding to a not in the chromatic scale.

5. A sound reproducing device comprising a closed end pipe and a pair ofopen end pipes, said pi es being joined end to end whereby two o saidpipes extend on the same axis and the other of said pipes extends atright angles thereto, means for imparting vibrations thereto, each ofsaid pi es comprising a resonating chamber and being tuned to adifferent frequency whereby said various frequencies are reproduced insubstantially their original proportion.

6. A sound reproducing device comprising a pluralit of pi es, said pipesbeing joined end to en where y two o said pipes extend end to endwhereby two of said pipes extend. Aon the saine axis and another of saidpipes extends at right angles thereto, means for imparting vibrationsthereto, one of said pipes terminating in a bcll for allowing soundwaves to be impressed upon the surrounding medium, each of said pipescomprising a resonating chamber and being tuned to a different frequencywhereby said various frequencies are reproduced in substantially theiroriginal proportion..

8. A sound reproducing device comprising a closed end pipe and a pair ofopen end pipes, said pipes being joined end to end whereby two of saidpipes extend on the same axis and the other said pipes extends at rightangles thereto, said last mentioned pipe terminating in a bell forallowing sound waves to be impressed upon the surrounding medium, meansfor imparting vibrations thereto, each of said pipes comprising aresonating chamber and being tuned to a different frequency whereby saidvarious frequencies are reproduced in substantially their originalproportion. Y

9. A device for reproducing musical notes comprising a plurality ofgroups of resonating chambers, one chamber in each of said groups beingtuned to a different fundamental note each of the other chambers of saidgroups being tuned to a harmonic thereof, and means associated with eachof said groups for imparting sound waves thereto.

10. A device for reproducing musical'notes comprising a plurality ofgroups of resonating chambers, each of said groups being tuned to adifferent fundamentalnote of the musical scale, and the harmonicsthereof, and means associated with each of said groups for impartingsound waves thereto.

Signed at New York, in the county of New York and State of New York,this 23rd day of May, A. D. 1927.

MILLER REESE HUTCHISON.

